This invention relates in general to a device for reducing wave motion in waterbed mattresses, and more particularly to a wave reducing device of the hydraulic chamber type having a bouyant insert to locate the hydraulic chamber for optimum wave motion reduction.
Floatation sleep systems, commonly referred to as waterbeds, have become a popular alternative to conventional bedding due to their ability to give a more comfortable and relaxing sleep. This superior sleep is attributable, at least in part, to the substantially uniform pressure distribution exerted on the body when lying on the surface of the waterbed mattress. However, historically, objections to waterbeds have been based primarily on their propensity for extensive surface movement when a body supported on the mattress bladder changes position. The extensive movement is due to reflected wave action of the water within the bladder, initially induced by the changing of the location of displacement when the supported body moves on the surface of the bladder. Recent attempts to reduce wave motion have included utilizing a filler material, such as fiber and foam for example, within the bladder of the waterbed mattress. Such material has certain drawbacks which make their use less than desireable. Specifically, the fiber and foam react with the water to promote the growth of fungi and algae, and further they retain water so that complete draining of the bladder is not possible.
Another mechanism by which reduction of wave motion has been attempted is the inclusion of a device within the bladder which acts as a baffle to the flow of water within the bladder. One particularly effective baffle device is typically referred to as an hydraulic chamber. The hydraulic chamber comprises a compartment having a plurality of ports for allowing the water to move in and out of the compartment. The ports are of sufficient size to enable the water to move relatively freely into and out of the comparrtment when the mattress bladder is filled or drained, but restricts rapid transient flow of water induced by movement of a body supported on the surface of the mattress.
An example of a typical hydraulic chamber is shown in U.S. Pat. No. 4,607,404 (issued Aug. 26, 1986, in the name of Fraige). The hydraulic chamber of such patent includes a buoyant insert of interbonded, non-woven polyester fiber. The bouyant insert serves to float the top of the chamber just below the top surface of the mattress with the chamber hanging downwardly toward the bottom of the mattress. Such location of the chamber, enables the top surface of the mattress to exhibit a desireable feel to a body supported on the mattress. However, hydraulic chambers with buoyant inserts of this construction take time to stabalize against the top surface of the mattress when subjected to body movement on the surface, and further are subject to the above noted disadvantages of fiber in the water environment of the waterbed mattress.